The term déjà vu (French: "already seen", also called paramnesia) describes theexperience of feeling that one has witnessed or experienced a new situationpreviously. The term was created by a French psychic researcher, Emile Boirac(1851–1917) in his book L'Avenir des sciences psychiques (The Future of PsychicSciences), which expanded upon an essay he wrote while an undergraduate Frenchconcentrator at the University of Chicago. The experience of déjà vu is usuallyaccompanied by a compelling sense of familiarity, and also a sense of"eerieness" or "strangeness" or "weirdness". The "previous" experience is mostfrequently attributed to a dream, although in some cases there is a firm sensethat the experience "genuinely happened" in the past.The experience of déjà vuseems to be very common; in formal studies 70% or more of the population reporthaving experienced it at least once. References to the experience of déjà vu arealso found in literature of the past, indicating it is not a new phenomenon.However, in laboratory settings, it is extremely difficult to invoke the déjà vuexperience, making it a subject with few empirical studies.